Polysulfone/graphene oxide mixed matrix hollow fiber membrance for carbon dioxide removal

Abstract

The multiple benefits of membrane technology have promised the feasible application in large scale for carbon dioxide (CO2) removal. Mixed matrix membrane (MMM) is an organic polymeric phase that is dispersed with inorganic fillers. MMM has become a promising type of membrane for CO2 removal as it combines high processability of polymeric materials with superior gas separation properties of inorganic materials. In this study, an asymmetric mixed matrix hollow fiber membrane (MMHFM) was prepared by incorporating graphene oxide (GO) into polysulfone (PSf) polymer matrix for CO2 removal. Graphite was used as a filler precursor and was subjected to surface modification by oxidation process to produce graphene oxide (GO). Different loading of as-synthesized GO in the range between 0.05 to 1.0 wt.% was physically mixed with PSf polymer for dope preparation. The asymmetric MMHFM were spun via dry-wet technique. The transmission electron microscopy and atomic force microscopy analysis have confirmed that the synthesized GO was in the nanosheets form structure. The addition of GO was found to change the formation of MMHFM substructure layer as well as the thickness of MMHFM dense selective layer. The active functional groups of GO have facilitated the uniform filler dispersion within the PSf polymer matrix. GO loading of 0.25 wt.% was found to be the optimum loading to enhance the overall membrane properties and gas separation performance with CO2 permeance of 74.47 GPU. Both CO2/N2 and CO2/CH4 selectivity of MMHFM were enhanced by 310% and 211%, respectively, as compared to that of the neat PSf membrane. The well dispersed GO improves the CO2 separation by fully utilized its p-p conjugated bond and creates a path for small molecule gas (CO2) by restricting larger molecule gases (N2 and CH4) to pass through the membrane. However, the excessive of GO loading with more than 0.25 wt.% would lead to agglomeration and restacking problem, and this condition could deteriorate the MMHFM gas separation properties.